Cytotoxic drugs are often used to shrink primary tumors and prevent metastatic progression. However, these treatments are often systemic and not selective for cancer cells. Consequently, they must be injected in large doses to ensure that sufficient amounts reach the tumors. Because they are non-selective, they often kill healthy cells, resulting in serious side-effects. Biocompatible, non-toxic drug delivery systems have been developed; however, the FDA approved delivery systems, such as Abraxane®, Genexol-PM®, Doxil® and Onscaspar® serve only to improve the solubility of chemotherapeutic drugs. These delivery systems do not aid in targeting the drugs to tumors. Additionally, the diagnosis and imaging of tumor evolution remains a challenge.
The field of therapeutic diagnostics, or “theranostics”, aims to provide therapeutic, diagnostic and preventative medical treatments that cause minimal side-effects. Theranostics is an area of personalized medical care, in which researchers are focused on the development of new nanomaterials that both treat and diagnose cancer. Nanoparticle-based theranostics aim to decrease drug dosage by concentrating the drugs in tumors, while simultaneously providing a means of tumor imaging. Magnetic NPs are already used clinically as a contrast agent for magnetic resonance imaging (MRI) (Endorem®, Sinerem®).